Read from a log file as it's being written using python

Question

I'm trying to find a nice way to read a log file in real time using python. I'd like to process lines from a log file one at a time as it is written. Somehow I need to keep trying to read the file until it is created and then continue to process lines until I terminate the process. Is there an appropriate way to do this? Thanks.

Answer 1

Take a look at this PDF starting at page 38, ~slide I-77 and you'll find all the info you need. Of course the rest of the slides are amazing, too, but those specifically deal with your issue:

import time def follow(thefile):     thefile.seek(0,2) # Go to the end of the file     while True:         line = thefile.readline()         if not line:             time.sleep(0.1) # Sleep briefly             continue         yield line 

Answer 2

You could try with something like this:

import time  while 1:     where = file.tell()     line = file.readline()     if not line:         time.sleep(1)         file.seek(where)     else:         print line, # already has newline 

Example was extracted from here.